The invention relates to a sensor for an apparatus for measuring the level and/or the quantity of a liquid medium in a vessel, for example a pressure vessel, provided with a carrier which may be mounted in the wall of the vessel, a first pipe fastened to the carrier and a second pipe positioned concentrically and insulated within the first pipe, which second pipe may be connected through a bushing member positioned in the carrier.
A sensor of this type may for example be applied for measuring the level in a pressure vessel for liquid gas in a motor car. The two pipes together form a capcitor, of which the capacity value is dependent on the presence of the liquid gas between the two pipes. By means of an electronic circuit the level or the quantity of gas which is still present in the pressure vessel may be determined on the basis of the capacity value, so that the supply of fuel may be indicated to the user.
It is also possible to apply a sensor of this kind for determining the level and/or the quantity of the liquid gas in a storage tank with a fuelling station. Although the known sensor in practice functions satisfactorily for the application in a fuel tank, the accuracy for application in storage tanks may leave much to be desired, whereas with such applications it is moreover desirable to obtain a clear signalling at certain levels.